Cold tolerance of forage plant species

The occurrence of frost in southern and southeastern Brazil affects pasture quality and limits the use of forage species with high yield potential. Therefore, elucidating the cold tolerance of individual forage species could facilitate the selection of species that will optimize production and animal feeding throughout the year. Accordingly, the aim of the present study was to evaluate the cold tolerance of forage species to low temperatures, based on cell membrane stability and photoinhibition. Alfalfa (Medicago sativa), sorghum (Sorghum bicolor), black oat (Avena strigosa), marandu grass (Urochloa brizantha), pearl millet (Pennisetum americanum), mombaça grass (Megathyrsus maximus), and bermuda grass ‘Tifton 85’ (Cynodon spp) plants were subjected to temperatures of 0.2, -0.9, -1.8, -2.7, -4.1, -4.6, and -6.2 °C for 1 h in a growth chamber. Cell membrane stability and photoinhibition were based on the electrical conductivity of leaf section solutions and chlorophyll fluorescence, respectively. Initial cold damage corresponded to a sudden increase in leaf solution conductivity and decrease in fluorescence. Millet and sorghum were able to tolerate exposure to temperatures as low as -2.7 °C, whereas black oat, marandu grass, alfafa, and mombaça grass were able to tolerate exposure to -4.1 °C, and bermuda grass ‘Tifton 85’ was able to withstand temperatures below -6.2 °C

A comprehensive assessment of the transcriptome of cork oak (Quercus suber) through EST sequencing

Background: Cork oak (Quercus suber) is one of the rare trees with the ability to produce cork, a material widely used to make wine bottle stoppers, flooring and insulation materials, among many other uses. The molecular mechanisms of cork formation are still poorly understood, in great part due to the difficulty in studying a species with a long life-cycle and for which there is scarce molecular/genomic information. Cork oak forests are of great ecological importance and represent a major economic and social resource in Southern Europe and Northern Africa. However, global warming is threatening the cork oak forests by imposing thermal, hydric and many types of novel biotic stresses. Despite the economic and social value of the Q. suber species, few genomic resources have been developed, useful for biotechnological applications and improved forest management. Results: We generated in excess of 7 million sequence reads, by pyrosequencing 21 normalized cDNA libraries derived from multiple Q. suber tissues and organs, developmental stages and physiological conditions. We deployed a stringent sequence processing and assembly pipeline that resulted in the identification of ~159,000 unigenes. These were annotated according to their similarity to known plant genes, to known Interpro domains, GO classes and E.C. numbers. The phylogenetic extent of this ESTs set was investigated, and we found that cork oak revealed a significant new gene space that is not covered by other model species or EST sequencing projects. The raw data, as well as the full annotated assembly, are now available to the community in a dedicated web portal at http://www.corkoakdb.org. Conclusions: This genomic resource represents the first trancriptome study in a cork producing species. It can be explored to develop new tools and approaches to understand stress responses and developmental processes in forest trees, as well as the molecular cascades underlying cork differentiation and disease response.Peer Reviewe

Brazilian Consensus on Photoprotection

Brazil is a country of continental dimensions with a large heterogeneity of climates and massive mixing of the population. Almost the entire national territory is located between the Equator and the Tropic of Capricorn, and the Earth axial tilt to the south certainly makes Brazil one of the countries of the world with greater extent of land in proximity to the sun. The Brazilian coastline, where most of its population lives, is more than 8,500 km long. Due to geographic characteristics and cultural trends, Brazilians are among the peoples with the highest annual exposure to the sun. Epidemiological data show a continuing increase in the incidence of nonmelanoma and melanoma skin cancers. Photoprotection can be understood as a set of measures aimed at reducing sun exposure and at preventing the development of acute and chronic actinic damage. Due to the peculiarities of Brazilian territory and culture, it would not be advisable to replicate the concepts of photoprotection from other developed countries, places with completely different climates and populations. Thus the Brazilian Society of Dermatology has developed the Brazilian Consensus on Photoprotection, the first official document on photoprotection developed in Brazil for Brazilians, with recommendations on matters involving photoprotection

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Avaliação da qualidade fisiológica de sementes de mamoneira (Ricinus communis L.) pelo teste de tetrazólio

O teste de tetrazólio é um método rápido e eficaz para avaliar a viabilidade e o vigor de sementes. O presente trabalho teve por objetivo padronizar a metodologia do teste de tetrazólio para a avaliação da qualidade fisiológica de sementes de mamoneira (Ricinus communis L.). A pesquisa foi realizada em quatro etapas. Na primeira, testou-se o método de preparo das sementes (corte longitudinal mediano através do tegumento, endosperma e embrião; corte longitudinal diagonal na região distal da carúncula sem atingir o eixo embrionário; remoção do tegumento; remoção do tegumento com corte longitudinal mediano através do endosperma e embrião; e remoção do tegumento com corte longitudinal mediano, paralelo aos cotilédones, através do endosperma e embrião), avaliando-se a coloração. Na segunda, a concentração da solução de tetrazólio (1,0%, 0,5%, 0,2%, 0,1% e 0,075%) e o período de coloração (30 a 240 minutos) foram estudados e os resultados comparados com os obtidos nos testes de germinação. Na terceira, testaram-se os métodos de pré-condicionamento das sementes (entre papel umedecido, sementes com tegumento, por 6, 8, 10, 12, 14, 16 e 18 horas, a 30ºC, 35ºC e 40ºC; entre papel umedecido, sementes sem tegumento, e imersão em água das sementes com tegumento, ambos por 1, 2, 3, 4, 5 e 6 horas, a 25ºC, 30ºC, 35ºC e 40ºC), sendo os resultados avaliados pela uniformidade na coloração e comparados aos obtidos no teste de germinação. Na quarta, avaliou-se a classificação dos lotes de sementes quanto à viabilidade e ao vigor pelo teste de tetrazólio, sendo os resultados comparados aos obtidos nos testes de germinação em areia, em papel, primeira contagem da germinação em papel, emergência de plântulas em campo, índice de velocidade de emergência, classificação do vigor de plântulas,...The tetrazolium test is a quick and accurate method for estimating seed viability and vigor. This research had the objective of standardizing the tetrazolium test methodology for the evaluation of physiological quality of castor bean seeds (Ricinus communis L.). The research was carried out in four parts. In the first one, seed preparation methods (longitudinal cut through the middle of the seed coat, endosperm and embryo; longitudinal and diagonal cut without reaching the embryo; coat removal; coat removal with longitudinal cut through the middle of the endosperm and embryo; and coat removal with longitudinal cut parallel to cotyledons through the middle of the endosperm and embryo) were evaluated by staining evaluations. In the second part tetrazolium solution concentrations (1.0%, 0.5%, 0.2%, 0.1% and 0.075%) and staining periods (30 to 240 minutes) were tested. The results were compared to the ones from the germination test. In the third part, seed preconditioning methods (between moist paper towel, seeds with coat, for 6, 8, 10, 12, 14, 16 and 18 hours, at 30ºC, 35ºC and 40ºC; between moist paper towel, seeds without coat, and seeds with coat immersed in water, both for 1, 2, 3, 4, 5 and 6 hours, at 25ºC, 30ºC, 35ºC and 40ºC) were evaluated and the results were evaluated by staining uniformity and compared with germination test values. In the fourth part, seed lot classification for viability and vigor were evaluated by the tetrazolium test and the results were compared to ones from the germination test in sand, in paper, first count of the germination test in paper, seedling emergence in the field, emergence speed index, seedling vigor classification, seedling length and dry matter and accelerated aging tests. All tests were conducted at the same time. The statistical design was completely randomized, and the means comparisons were accomplished...(Complete abstract click electronic access below)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES